RFID transponders are used in numerous different applications such as identification or passive or keyless entry systems. The most valuable and limited resource in any RFID transponder is power or energy the RFID needs for operation. Therefore, it is common practice that RFID transponders monitor the received radio frequency signals and check whether or not they contain a specific wake pattern. For this purpose, conventional RFID transponders include a wake pattern mechanism which continuously monitors the incoming signals and issues a wake signal for other components of the RFID transponder if the wake pattern is detected. However, although a substantial amount of power can be saved since the most power consuming parts of the RFID transponder are in power-down mode until the wake pattern is detected, it is desirable to further reduce power consumption.
Keyless entry systems and passive entry systems to which the present invention can advantageously be applied are known from U.S. Pat. No. 6,323,566 B1 and U.S. Pat. No. 6,489,886 B2.